In a transparent optical mesh network in which wavelength conversion is not performed between relay nodes, efficient use of wavelength free bands becomes gradually unavailable by repeating setting and deleting of a wavelength path, and there is a fear that the amount of network equipment increases. Also, as for an upper layer path such as OTN (Optical Transport Network), SDH (Synchronous Digital Hierarchy), VCAT (Virtual Concatenation) or the like, it is considered that efficiency of accommodation in a wavelength path becomes worse by repeating path setting and deletion.
In order to solve these problems, a method of reallocating a wavelength path (refer to non-patent document 1), and a method for changing capacity and route of a path (refer to patent document 1) are proposed.